/Engine/Plugins/Online/OnlineSubsystemUtils/Source/OnlineSubsystemUtils/Public/PartyBeaconClient.h
Sends an update request to the remote host to append additional members to an existing party in the host's session. Note this request is async.
true if the request able to be sent, false if it failed to send
virtual bool RequestReservationUpdate ( const [FString](API\Runtime\Core\Containers\FString) & ConnectInfoStr, const [FString](API\Runtime\Core\Containers\FString) & InSessionId, const [FUniqueNetIdRepl](API\Runtime\Engine\GameFramework\FUniqueNetIdRepl) & RequestingPartyLeader, const [TArray](API\Runtime\Core\Containers\TArray)< [FPlayerReservation](API\Plugins\OnlineSubsystemUtils\FPlayerReservation) > & PlayersToAdd, bool bRemovePlayers )